To enable the robot's speaking abilities, engineers at Japan's Kagawa University used an air pump, artificial vocal chords, a resonance tube, a nasal cavity, and a microphone attached to a sound analyzer as substitutes for human vocal organs. The robot not only talks, but it uses a learning algorithm to mimic the sounds of human speech. By inputting the voices of both hearing-impaired and non-hearing-impaired people into the microphone, researchers were able to plot the differences in sound on a map. During speech training, the robot "listens" to the subjects talk while comparing their pronunciation to that of subjects who are not hearing-impaired. The robot then generates a personalized visualization that allows subjects to adjust their pronunciation according to the target points on the speech map.